Quantitative determination of serum bile acids using a purified 3 alpha-hydroxysteroid dehydrogenase

A specific, simple, and reliable method for the quantitative determination of 3 alpha-hydroxy bile acids in serum in described. It is based on the specific enzymatic conversion of the 3alpha-hydroxyl group of the steroid molecule using a highly purified 3alpha-hydroxysteroid dehydrogenase and fluorimetric determination of NADH. A liquid-solid extraction employing Amberlite XAD-2 has been used. Overall recovery of the major human bile acids from normal and jaundiced serum averaged 91.2%. The range of normal values for serum bile acids was found to be 0.9-6.3 mumoles/1 (mean 3.0).